Natural environment and culture influence indigenous plant knowledge

Firstly, these differences might be caused by the distribution of the plants. The research areas are not the same size, and the geographical and climatic environments and vegetation types are different [52]. Gyirong and Yadong include tropical to subtropical climate, and the main vegetation type is coniferous broad-leaved mixed forest (Fig. 6). However, Burang Town belongs to the temperate arid climate, and the main vegetation types are desert grassland (Fig. 6) [53]. Although there are differences in the utilization of plants in the three areas, there are still some plants that reflect the common preferences of them. For example, Carum carvi, an important wild vegetable and seasoning in Tibetan regions, ranked top 5 in CII value in all three regions. The use of Tibetan incense plants such as Juniperus indica and Rhododendron anthopogon also reflects the common cultural characteristics of the Tibetan people. In addition, Neopicrorhiza scrophulariiflora and Saussurea tridactyla also show the current situation of the spread of plant culture driven by the economy [22, 27].

To sum up, different natural environments may lead to different plant utilization. For example, there are obvious differences between Yadong, Gyirong and Burang, and each region has its own special plant knowledge. Previous studies have noted that geographical isolation could contribute to the preservation of diverse cultural traditions of local people in Himalayan regions [54] and could help preserve diverse traditional botanical knowledge. Our study also shows that the same cultural groups have common cultural preferences, for example, 11 plant species are shared across the three areas.

Important wild useful plants

Based on the results of the CII quantitative analysis, we evaluated the top five wild plants that are important in the daily life of Tibetans in Gyirong Town.

Allium prattii C.H.Wright (CII = 1.071) is an important edible plant in Gyirong. Its young leaves and bulbs can be consumed as wild vegetables, and its fruits and flowers can be eaten as seasonings. A local woman said:

Ri guo (A. prattii) is a very delicious seasoning, you can use it for stewing potatoes or meat. There's a lot of it on the mountain that we pick it for consuming or selling.

This reflects two aspects of the plant, the first is that it is a delicacy that locals enjoy. In addition, it is easy to obtain. This plant is widely distributed in the Himalayas of China and northern India and Nepal [55]. It is also used as an edible plant in other areas. For example, it has the same usage as Gyirong in Yadong County, Tibet [22]. In Litang, Sichuan, China, the Tibetans also use the fresh bulb of the plant as a wild vegetable and spice [32]. In addition, it is also used to increase appetite and treat digestive system diseases, which was recorded in the Tibetan medical scripture “Jing Zhu Ben Cao” [56].

Neopicrorhiza scrophulariiflora (Pennell) D. Y. Hong (CII = 1.016) has important practical and economic value, which also drives the local people to collect it. Locals grind the dried root and drink it with boiling water to treat inflammation or fever. The plant is mainly distributed in the eastern Himalayas, at the junction of China and Nepal [55]. Neopicrorhiza scrophulariiflora was widely used by the locals to treat cold. This plant was first recorded in the “Si Bu Yi Dian and was mainly used to treat fever [23, 57]. According to the Chinese Pharmacopoeia, this plant can treat many diseases [42]. In the Yadong County of the Himalayas and Maithili region of eastern Nepal, it is used by locals to treat fever and headaches with high consensus [30].

Gymnadenia orchidis Lindl. (CII = 0.921), its root is an important tonic, the local people cook it with chicken, duck or milk, which can nourish the body. It is a traditional Tibetan medicinal plant for nourishing which was documented in “Jing Zhu Ben Cao” [56]. It was first recorded in the Tibetan medical work “Four Medical Canons” born in the eighth century AD [23]. The roots also were sold to increase income.

Rhododendron anthopogon D. Don(CII = 0.873)is an important ritual plant for “Sang” (People burn some plants in the morning to pray for a peaceful day) [58], the distribution range of R. anthopogon is almost all over the Himalayas, so is relatively easy to obtain [55]. An informant mentioned:

“We have to burn incense plants every morning, which smell good and can refresh us.”

When we ask what plants are best. He replied:

“Polu (R. anthopogon) is the best.”

The local Tibetans collect the old leaves of R. anthopogon and sun-dry them as materials for “Sang.” In addition to R. anthopogon, Juniperus indica and Artemisia sp. are important materials for “Sang.” R. anthopogon is also a beverage plant for local people to drink and sell. Its flowers are collected and sun-dried and then soaked in water to drink. It has a unique flavor, but drinking too much will cause headaches, which may be related to the toxic ingredients contained in it. According to the Chinese Pharmacopoeia, its flowers and leaves are used separately in Tibetan medicine, and its flowers can be taken as tea, which has a good curative effect on asthma and chronic bronchitis [59].

The bulbs of Fritillaria cirrhosa D. Don (CII = 0.857) were used by the locals to treat colds and coughs, and the main processing method is decoction. In addition, F. cirrhosa is also an important economic plant and a veterinary medicinal plant. It is recorded in the Chinese “Materia Medica and Tibetan Medicine Volume” that F. cirrhosa has the effect of resolving phlegm and relieving cough [23]. Fritillaria cirrhosa, which has high commercial value, has been excessively and indiscriminately harvested. As a result, its resources are declining sharply, and it is on the verge of extinction [60].

In particular, of these top five plant species, four were driven by economic value and one was driven by culture. This reflects to a certain extent that the main driving force for the spread of plant utilization knowledge is the economy.

The state of traditional knowledge of wild useful plants in Gyirong

Tibetans of Gyirong have a wealth of knowledge. Most of the people who have acquired knowledge among the Tibetans of Gyirong are middle-aged, and these people have more voice and power in social life. Young people are reluctant to learn traditional plant knowledge [9]. Therefore, with the development of social economy and time, traditional knowledge is slowly disappearing or changing into other forms, such as knowledge about the economic plants. Protecting and documenting preexisting botanical knowledge is important and urgent.

Traditional wild plants’ knowledge of local Tibetans is also heavily influenced by traditional Tibetan medicine and tourism [9, 26]. The plant knowledge of the Tibetans in Gyirong is influenced by the traditional Tibetan medicine culture. In the cataloging of this study, 26 species were documented in traditional Tibetan medicine books [23]. In addition, locals sell many wild plants in the store, including various seasonings and medicines, and these products are mainly aimed at tourists. With the development of commerce, the excessive collection of plants has caused a certain degree of damage to the local ecological environment [61].

Local people not only use wild plants to meet their own needs but can also profit from wild plants. According to local government statistics on the basic situation of the township, the understory economy of wild plants has become an important source of economic income for locals. For example, Fritillaria cirrhosa and Neopicrorhiza scrophula are suffering from exhaustive collection. In addition, there are 11 other plant species under different levels of protection, but these plants are not protected because of commercialization [51].

Gyirong Tibetans have a rich traditional knowledge of wild plants, which has been influenced by the traditional Tibetan medicine culture. With the development of the social economy, their traditional knowledge of plants has also been affected by tourism culture, and the economy has gradually become the important driving force of wild plant collection.

The relevance of this study for the development of the local community

Locally, the economy has become the main driver of the use of local plants. This phenomenon, if not restricted, may lead to the overharvesting of wild plants. Although local people obtain permits before collecting the fungus, there are no special management measures for collecting other wild plants. It is worth noting that the impact of the current tourism economy has made local traditional knowledge increasingly narrow. Previous studies have shown that biodiversity loss not only negatively affects the ecology and environment, but also culture, with profound implications for cultural resilience and biocultural diversity conservation efforts [62]. Therefore, if local communities want to achieve sustainable use of wild economic plants, we should not only pay attention to the protection of biodiversity, but also pay attention to the importance of traditional culture [63]. Local communities should carry out protection activities from the aspects of the restricted collection of economic plants and recording and publicizing traditional knowledge.

Although wild edible plants can provide additional nutritional supplements to local people, we should also pay attention to the possible harm of some plants when they are consumed. According to previous reports, Pteridium aquilinum var. latiusculum is a nutritious wild vegetable. If it is not soaked for enough time and cooked, the toxic carcinogens contained in the plant will not be removed [64, 65]. It contains Anthraquinones (AQs) in Rheum australe. An increasing number of studies have reported that AQs induce nephrotoxicity [66]. The young leaves of Phytolacca acinosa are used as wild vegetables, but the red roots of it are poisonous and inedible [55]. Therefore, the food safety of wild edible plants should also be an issue for community development.